This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. To assess whether prolactin and oxytocin, commonly thought to be important in parent-offspring relationships is also [unreadable] important in adult relationships between mates.[unreadable] [unreadable] Prolactin is necessary for successful nursing in mammals, and also regulates maternal behavior. In some biparental species [unreadable] of birds and mammals prolactin levels are elevated in fathers, and there is some evidence that prolactin may be important [unreadable] for quality male care of infants. Prolactin, thus, is often thought of as a "parental" hormone. Oxytocin is also involved in [unreadable] maternal care but has recently been implicated in pairbonding in monogamous rodents. Are there other conditions where [unreadable] elevated prolactin and oxytocin might be important? Parental care represents one type of social relationship, and [unreadable] "parenting" hormones might be important in other social relationships. We have found significant positive correlations [unreadable] between prolactin and oxytocin levels and affiliative behavior (huddle, groom), and sexual behavior in both male and [unreadable] female cotton-top tamarins (Saguinus oedipus). Mates that engaged in more positive social interactions with their mates [unreadable] had higher hormone levels. We examined the potential causal relationship between affiliation and prolactin by [unreadable] administering cabergoline, a dopamine agonist that reduces prolactin levels. Cabergoline did not alter affiliative behavior, [unreadable] but at the same time the control condition did not replicate our previous studies by correlating with prolactin levels. [unreadable] However, we did replicate the finding that there is great variation in relationship quality among different pairs. We have [unreadable] replicated data on affiliative relationships in 15 mated pairs and can correlate oxytocin levels to relationship quality. This [unreadable] work relied on the WNPRC Assay Services and Library and Information Services.